docs: def normalizeURL(url):
      """Normalize a URL, converting normalization failures to
      DiscoveryFailure"""
      try:
          normalized = urinorm.urinorm(url)
      except ValueError, why:
          raise DiscoveryFailure('Normalizing identifier: %s' % (why[0],), None)
      else:
          return urlparse.urldefrag(normalized)[0]